1. Technical Field
The present invention relates to a universal haptic drive system for arm and wrist rehabilitation.
2. Description of Related Art
Upper extremity function is of paramount importance to carry out various activities of daily living. Various neurological diseases, most notably stroke, as well as orthopaedic conditions result in impaired function of manipulating various objects by reaching, orienting and grasping activities. Reaching or approaching toward an object is done by shoulder and elbow, orienting of and object is accomplished by wrist, while grasping and releasing of an object is carried out by opening and closing a hand.
After an injury or neurological impairment intensive physiotherapy is employed through active-assisted targeted movement and exercises aiming at restoration of sensory-motor planning, reduction of spasticity and preservation of range of motion to facilitate recovery of the arm and hand functionality. Numerous clinical studies have shown that a key to successful recovery is a sufficient number of repetitions that relate to a practiced task. Here two basic approaches can be distinguished: complex movement practice that involves reaching, orienting and grasping activities combined in a single task and isolated well-defined specific movement training of each isolated component of upper extremity function. Training specificity determines also therapy outcome; i.e. reaching exercises activate shoulder and elbow thus resulting in improvement of transport of the hand toward target location; movement of forearm and wrist exercises that serve to orient the hand and provide stability and control during grasping result in improvement of wrist function, while grasping and releasing exercises result in improvement of grasping function. The above outlined movement practice is facilitated by a physiotherapist that employs verbal communication as well as physical interaction to guide a trainee to appropriately execute a given task.
Rehabilitation robotics seems to be particularly well suited for delivery of mass-practiced movement. It brings precision, accuracy and repeatability and combined with computer or virtual reality tasks provide stimulating training environment. Impedance control of rehabilitation robots enables programmable haptic interaction with the paretic arm and hand. Such a haptic interaction is needed to initiate, guide and halt movement depending on the activity of the user. It has been demonstrated in numerous clinical studies that these features of rehabilitation robots yield significant rehabilitation results.
The current state of the art includes haptic robotic solutions that have from one to three haptic degrees of freedom and were developed for training of the shoulder and elbow. Examples are MIT-MANUS described in U.S. Pat. No. 5,466,213 (Hogan et al.), and ARM Guide and EMUL described in an article by Krebs et al., Robotic rehabilitation therapy, Wiley encyclopaedia of Biomedical Engineering, John Wiley & Sons, 2006. Other robotic solutions were developed for wrist, such as BI-MANU-TRACK, described by Hesse et al., Upper and lower extremity robotic devices for rehabilitation and studying motor control, Current Opinion in Neurology 2003, 16: 705-710 and MIT wrist robot described in the earlier cited article by Krebs et al. MIT-MANUS is a two-degrees-of-freedom, SCARA-type, planar impedance controlled robot that enables practicing of reaching movement in horizontal plane by activating shoulder and elbow. With MIT-MANUS it is not possible to practice movement along the vertical axis. EMUL is a three-degrees-of-freedom, PUMA type, impedance controlled robot that enables practicing reaching movement of the arm within the whole workspace, including the vertical axis. ARM Guide on the other hand is a single degree-of-freedom impedance controlled robot that enables movement of the arm (shoulder and elbow) along the line and can be oriented in different directions within the 3D workspace to enable practicing of reaching movement in different parts of a workspace. BI-MANU-TRACK is a device that offers active (motor assisted) or passive training of wrist flexion/extension or (depending on the mechanical configuration of the device) forearm pro/supination following bi-lateral approach, meaning that the un-impaired side drives movement of impaired side in a mirror-like or parallel fashion. MIT wrist robot is a three-degrees-of-freedom device that has three impedance controlled axis that intersect with all three human wrist degrees-of-freedom (flexion/extension, abduction/adduction and pronation/supination) enabling simultaneous practicing of wrist orientation movement. The common denominator for the above devices is that for exhibiting compliant (impedance controlled) performance the actuated degrees of freedom need to be back-drivable, meaning that the inherent impedance of actuators must be low. This necessitates use of direct drive, high torque motors as well as use of precise position and force sensors. Another drawback of the known devices is that they provide training environment for only one component/activity of reaching movement, either reaching movement or wrist movement.